Flexible polyurethane foam

Abstract

A flexible polyurethane foam comprising: a first surface having a surface porosity of 20-60%; and a second surface having a surface porosity of 0-1.0%.

Description

Flexible polyurethane foam

[0001] This disclosure relates to flexible polyurethane foam.

[0002] Flexible polyurethane foam is used in a wide range of applications, including household goods, automotive interior materials, clothing, sports and leisure goods, medical materials, and civil engineering and construction materials. For example, it is used as a soundproofing material, such as a sound-absorbing or sound-insulating material to reduce noise. For instance, Patent Document 1 discloses a polyurethane foam for sound insulation and absorption, in which the core density and rebound elasticity are within a specific range, resulting in particularly good sound absorption coefficient in the high-frequency range of 2000 Hz or higher.

[0003] Japanese Patent Publication No. 2004-124076

[0004] Noise is generated by a wide variety of factors, and consequently, the frequency range of the resulting noise also varies. Therefore, a soundproofing material that exhibits excellent sound absorption across a wide frequency range (especially 1000-6300 Hz) as well as superior sound insulation in the low and medium frequency range (especially 630-1600 Hz) would be useful.

[0005] However, conventional polyurethane foams have room for improvement in terms of sound absorption across a wide frequency range and sound insulation in the low and medium frequency ranges. Therefore, the object of this disclosure is to provide a flexible polyurethane foam that exhibits high sound absorption across a wide frequency range, particularly in the 1000 to 6300 Hz frequency range, and high sound insulation in the low and medium frequency range, particularly in the 630 to 1600 Hz frequency range.

[0006] This disclosure provides the following [1] to [6].

[0007] [1] A flexible polyurethane foam having a first surface with a surface porosity of 20 to 60% and a second surface with a surface porosity of 0 to 1.0%.

[0008] [2] Bulk density of 80-140 kg / m³ ３ The flexible polyurethane foam described in [1].

[0009] [3] A flexible polyurethane foam according to [1] or [2], wherein the average cell diameter is 0.3 to 0.8 mm.

[0010] [4] The flexible polyurethane foam according to any one of [1] to [3], which has an F hardness of 25 to 95.

[0011] [5] The air permeability measured in accordance with JIS K 6400-7:2012 is 0 to 1.0 cm ３ / cm ２ / sec, which is the flexible polyurethane foam according to any one of [1] to [4].

[0012] [6] The flexible polyurethane foam according to any one of [1] to [5], which has a thickness at the thinnest portion of 5.0 to 50 mm.

[0013] According to the present disclosure, there is provided a flexible polyurethane foam that exhibits high sound absorption properties in a wide frequency range, particularly in a frequency range of 1000 to 6300 Hz, and exhibits high sound insulation properties in a low to medium frequency range, particularly in a frequency range of 630 to 1600 Hz.

[0014] Hereinafter, embodiments of the present disclosure will be described in detail. In the present disclosure, a numerical range indicated by using "~" indicates a range including the numerical values described before and after "~" as the minimum value and the maximum value, respectively. Unless explicitly stated otherwise, the units of the numerical values described before and after "~" are the same. In addition, each configuration and parameter can be arbitrarily combined, and the upper limit values and lower limit values described individually can be arbitrarily combined. In addition, unless otherwise specified, the materials exemplified below may be used alone in one kind, or may be used in combination of two or more kinds.

[0015] The flexible polyurethane foam according to the present disclosure includes a first surface having a surface opening rate of 20 to 60% (hereinafter, also simply referred to as "first surface"), and a second surface having a surface opening rate of 0 to 1.0% (hereinafter, also simply referred to as "second surface"). When the surface opening rate of the first surface is 20% or more, the sound absorption property is sufficiently enhanced in a wide frequency range, particularly in a frequency range of 1000 to 6300 Hz. In addition, when the surface opening rate of the second surface is 1.0% or less, the sound insulation property is sufficiently enhanced in a low to medium frequency range, particularly in a frequency range of 630 to 1600 Hz.

[0016] Flexible polyurethane foam refers to reversibly deformable foam having an open-cell structure and exhibiting high air permeability [see, for example, Gunter Oertel, "Polyurethane Handbook" (1985 Edition), Hanser Publisher (Germany), pp. 161-233, and Keiji Iwata, "Polyurethane Resin Handbook" (First Edition 1987), Nikkan Kogyo Shimbun, Ltd., pp. 150-221].

[0017] Although it is difficult to specifically define the physical properties of flexible polyurethane foam because they vary depending on chemical factors such as the chemical structures of polyols, isocyanates and the like used in production, the blending amount of the blowing agent, the isocyanate index, the cell structure, etc., in general, the density (measurable as apparent density; the same applies hereinafter) is 10 to 100 kg / m ３ (JIS K 6401), and the compressive strength (ILD 25%) is in the range of 2 to 80 kgf (20 to 800 N) (JIS K 6401) [see, for example, Gunter Oertel, "Polyurethane Handbook" (1985 Edition), Hanser Publisher (Germany), pp. 184-191 and pp. 212-218, and Keiji Iwata, "Polyurethane Resin Handbook" (First Edition 1987), Nikkan Kogyo Shimbun, Ltd., pp. 160-166 and pp. 186-191].

[0018] Semi-rigid polyurethane foam is a reversibly deformable foam that has higher foam density and compressive strength than flexible polyurethane foam, but has an open-cell structure similar to flexible polyurethane foam and exhibits high air permeability. The raw materials such as polyols and isocyanates used in its production are also the same as those for flexible polyurethane foam, so it is generally often classified as flexible polyurethane foam [see, for example, Gunter Oertel, "Polyurethane Handbook" (1985 Edition), Hanser Publisher (Germany), pp. 223-233, and Keiji Iwata, "Polyurethane Resin Handbook" (First Edition 1987), Nikkan Kogyo Shimbun, Ltd., pp. 211-221]. Although the physical properties of semi-rigid polyurethane foam are not particularly limited, in general the density is 40 to 800 kg / m ３, 25% compressive strength is 0.1–2 kgf / cm² ２ The range is (9.8 to 200 kPa).

[0019] In contrast, rigid polyurethane foam has a highly cross-linked closed-cell structure and is a foam that cannot be reversibly deformed, possessing properties completely different from those of flexible and semi-rigid polyurethane foam [see, for example, Gunter Oertel, "Polyurethane Handbook" (1985 edition), Hanser Publishing (Germany), pp. 234-313; Keiji Iwata, "Polyurethane Resin Handbook" (1987 first edition), Nikkan Kogyo Shimbun, pp. 224-283]. The properties of rigid foam are not particularly limited, but generally, the density is 20-100 kg / m³. ３ , compressive strength of 0.5 to 10 kgf / cm ２ The range is (50 to 1000 kPa).

[0020] In this disclosure, "flexible polyurethane foam" includes not only flexible polyurethane foam having the above-described properties, but also semi-rigid polyurethane foam having the above-described properties.

[0021] In this disclosure, the surface porosity of the first and second surfaces of the flexible polyurethane foam refers to the value obtained by the following procedure. First, the flexible polyurethane foam is cut out so that the measurement surface (first or second surface) is circular with a diameter of 28.8 mm. Next, an image with a diameter of 28.8 mm is taken of the measurement surface using a microscope equipped with a Moritex MM014-HR110-5M telecentric lens. Then, the above image is binarized using the software "ImageJ" to separate the porosity from the rest of the surface, and after calculating the sum of the areas of the porosity, the surface porosity is calculated based on the following formula: Surface porosity = (Sum of porosity areas / Sample area) × 100

[0022] The open pores on the first surface or the second surface of the flexible polyurethane foam may be pores formed along with the foaming of the flexible polyurethane foam, or may be pores provided by physical treatment after the flexible polyurethane foam is foamed. Examples of the physical treatment include perforation with a needle. When the flexible polyurethane foam is molded by mold molding, the surface open pore ratio attributed to pores formed along with foaming can be adjusted depending on the type of a release agent or the like described later.

[0023] From the viewpoint of exhibiting higher sound absorption, the surface open pore ratio of the first surface of the flexible polyurethane foam may be 30% or more, 40% or more, or 44% or more, may be 55% or less, 50% or less, or 46% or less, and may be 30 to 55%, 40 to 50%, or 44 to 46%.

[0024] From the viewpoint of exhibiting higher sound insulation, the surface open pore ratio of the second surface of the flexible polyurethane foam may be 0.8% or less, 0.5% or less, or 0.1% or less, and may be 0 to 0.8%, 0 to 0.5%, or 0 to 0.1%.

[0025] The bulk density of the flexible polyurethane foam may be 80 to 140 kg / m ３ . When the bulk density of the flexible polyurethane foam falls within the above range, the flexible polyurethane foam tends to be excellent in rigidity and durability. From the same viewpoint, the bulk density of the flexible polyurethane foam may be 90 kg / m ３ or more, 100 kg / m ３ or more, or 115 kg / m ３ or more, and may be 130 kg / m ３ or less, 120 kg / m ３ or less, or 118 kg / m ３ or less, and may be 90 to 130 kg / m ３ , 100 to 120 kg / m ３ or 115 to 118 kg / m ３ . In the present disclosure, the bulk density is the apparent density of the entire flexible polyurethane foam measured in accordance with JIS K 6400-1:2004 (unit: kg / m ３This means that a rectangular sample (200 mm long x 200 mm wide x 10 mm thick) is cut from a flexible polyurethane foam and its weight (W) is measured. Next, the volume (V) is determined from the length, width, and thickness of the rectangular sample, and the bulk density (ρ) is calculated by dividing the weight (W) by the volume (V).

[0026] The average cell diameter of the flexible polyurethane foam may be 0.3 to 0.8 mm. When the average cell diameter of the flexible polyurethane foam is within the above range, good molding stability tends to be obtained. From a similar viewpoint, the average cell diameter of the flexible polyurethane foam may be 0.4 mm or more or 0.5 mm or more, 0.7 mm or less or 0.6 mm or less, or 0.4 to 0.7 mm or 0.5 to 0.6 mm.

[0027] In this disclosure, the average cell diameter of the flexible polyurethane foam refers to the value obtained by the following procedure. First, a sample for measurement is obtained by cutting out a circular shape with a diameter of 28.8 mm from a 10 mm thick flexible polyurethane foam. Next, an image with a field of view of 5.4 mm vertically and 7.2 mm horizontally is taken of the side surface (cut surface) of the sample for measurement using a microscope equipped with a Moritex MML08-HR110 lens. Next, four line segments are drawn in the vertical and horizontal directions on this image, and the number of cells located on each line segment is measured and the arithmetic mean is calculated to obtain the average number of cells. The average cell diameter is obtained by dividing the actual distance of each line (vertical: 5.4 mm, horizontal: 7.2 mm) by the average number of cells. Then, the average cell diameter is obtained by dividing the average cell diameter by 0.785, when the cell is considered as a circle.

[0028] The F hardness of the flexible polyurethane foam may be between 25 and 95. When the F hardness of the flexible polyurethane foam is within the above range, it tends to exhibit superior rigidity. From a similar viewpoint, the F hardness of the flexible polyurethane foam may be 50 or more, 70 or more, or 90 or more, or 94 or less, or 93 or less, or 50 to 94, 70 to 93, or 90 to 93. In this disclosure, F hardness refers to the value measured on the first surface using a rubber hardness tester (Asker F type). F hardness can be improved, for example, by including a crosslinking agent in the flexible polyurethane foam forming composition described later (more specifically, for example, an active hydrogen-containing compound separated from polyisocyanate (A) in the composition).

[0029] The air permeability of soft polyurethane foam is 0 to 5.0 cm. ３ / cm ２ / sec may be used, and from the viewpoint of showing higher sound insulation, 1.0 cm ３ / cm ２ / sec or less, 0.8cm ３ / cm ２ / sec or less or 0.3cm ３ / cm ２ It may be less than or equal to / sec, and between 0 and 1.0 cm. ３ / cm ２ / sec, 0-0.8cm ３ / cm ２ / sec or 0-0.3cm ３ / cm ２ It may also be / sec. In this disclosure, the air permeability means a value measured in accordance with JIS K 6400-7:2012 with respect to the foaming direction of the flexible polyurethane foam. Here, the foaming direction refers to the direction in which the foaming liquid for forming the flexible polyurethane foam, described later, increases in thickness when it foams in the mold, and the foam (cells) that are formed usually have a shape that extends in the thickness direction (for example, spindle-shaped), so the foaming direction can be determined from that shape. In this disclosure, the air permeability is measured through the first surface and the second surface.

[0030] Flexible polyurethane foam can have any shape, for example, it may be in the form of a sheet (including a film). The first and second surfaces of the flexible polyurethane foam may be opposing surfaces, from the viewpoint that molds with an upper and lower mold are often used during molding. If the flexible polyurethane foam is in the form of a sheet, one of the main surfaces may be the first surface, and the other opposing main surface may be the second surface. The first and second surfaces of the flexible polyurethane foam do not need to be flat; they may be curved or have irregularities.

[0031] The thickness of the thinnest part of the flexible polyurethane foam may be, for example, 5.0 to 70 mm, or 5.0 to 50 mm. A thickness of 5.0 mm or more at the thinnest part of the flexible polyurethane foam tends to provide better sound absorption. From a similar viewpoint, the thickness of the thinnest part of the flexible polyurethane foam may be 7.5 mm or more, or 10 mm or more. Also, a thickness of 50 mm or less at the thinnest part of the flexible polyurethane foam ensures sufficient space when installed as a soundproofing material. From a similar viewpoint, the thickness of the thinnest part of the flexible polyurethane foam may be 30 mm or less, or 20 mm or less. From these viewpoints, the thickness of the thinnest part of the flexible polyurethane foam may be 5.0 to 30 mm, 7.5 to 30 mm, or 10 to 20 mm.

[0032] The flexible polyurethane foam relating to this disclosure includes, for example, a polyisocyanate (A), a castor oil-based polyol (B1), and a polyether polyol (b2) having two hydroxyl groups. ｐｒｉThe composition may be a reaction product of a composition containing a polyether polyol (B2) containing (B1) and a blowing agent (C) (hereinafter also referred to as the "composition for forming flexible polyurethane foam"). The above composition for forming flexible polyurethane foam may also contain active hydrogen-containing compounds other than castor oil-based polyol (B1) and polyether polyol (B2) (hereinafter also referred to as "other active hydrogen-containing compounds"). In this disclosure, an active hydrogen-containing compound is a compound having active hydrogen that reacts with an isocyanate group, and typically has active hydrogen groups such as OH, NH, and SH, which react with isocyanate to form a urethane bond, a urea bond, and a thiourethane bond, respectively.

[0033] Polyisocyanate (A) can be any compound having two or more isocyanate groups. From the viewpoint of high reactivity of the isocyanate groups and good curing properties, diphenylmethane diisocyanates (hereinafter referred to as MDI), such as 4,4'-diphenylmethane diisocyanate (hereinafter referred to as 4,4'-MDI), 2,4'-diphenylmethane diisocyanate (hereinafter referred to as 2,4'-MDI), 2,2'-diphenylmethane diisocyanate (hereinafter referred to as 2,2'-MDI), polymethylene polyphenylene polyisocyanate (hereinafter referred to as P-MDI), and tolylene diisocyanate (hereinafter referred to as TDI) may be used as the isocyanate source. In this disclosure, various modified materials such as MDI, TDI, mixtures of MDI and P-MDI, mixtures of TDI and P-MDI, urethane modified materials, carbodiimide modified materials, urea modified materials, allophanate modified materials, isocyanurate modified materials, and biuret modified materials may also be used. Among these, a mixture of MDI and P-MDI may be used from the viewpoint of enabling the molding of flexible polyurethane foam over a wide density range.

[0034] The MDI content of polyisocyanate (A) relative to the total amount of MDI and P-MDI may be in the range of 50 to 85% by mass, from the viewpoint of easily obtaining polyurethane foam with high durability and scalability. When the MDI content is 85% by mass or less, the durability of the flexible polyurethane foam is improved, while when the MDI content is 50% by mass or more, the crosslinking density is appropriately suppressed, and the flexible polyurethane foam tends to have sufficient strength.

[0035] Furthermore, the sum of the content of 2,2'-MDI and the content of 2,4'-MDI relative to the total amount of MDI (hereinafter referred to as the isomer content) may be 10 to 50% by mass, and may also be 10 to 30% by mass from the viewpoint of high reactivity and shortening the molding cycle.

[0036] Having a 2,2'-MDI and 2,4'-MDI content of 10% by mass or more relative to the total amount of MDI improves the storage stability of the polyisocyanate composition at low temperatures. It also improves the molding stability of the flexible polyurethane foam and suppresses foam collapse during foaming. On the other hand, having a content of 50% by mass or less improves reactivity, extends the molding cycle, increases the foam's cell locking ratio, and suppresses problems such as shrinkage after molding.

[0037] The isomer ratios, such as the content of the 2,4-isomer and the 2,6-isomer relative to the total amount of TDI, are not particularly limited.

[0038] The TDI content relative to the total amount of TDI and P-MDI may be 20 to 80% by mass.

[0039] The polyisocyanate (A) content in the flexible polyurethane foam forming composition according to this disclosure may be 30 to 80% by mass or 40 to 70% by mass, based on the total mass of the flexible polyurethane foam forming composition.

[0040] The content of polyisocyanates, polyethers, and polyols in a composition for forming flexible polyurethane foam can be measured by known methods. For example, it can be measured by separating the decomposed composition obtained by alkaline hydrolysis of the flexible polyurethane foam obtained using the composition and measuring the weight of each component, or by performing elemental analysis related to nitrogen.

[0041] Examples of castor oil-based polyols (B1) include castor oil (refined castor oil, semi-refined castor oil, unrefined castor oil, etc.), hydrogenated castor oil obtained by adding hydrogen to castor oil, and other castor oil-modified polyols, and castor oil itself may also be used. Castor oil is a triester of fatty acids and glycerol, and approximately 90 mol% of the total constituent fatty acids in castor oil is ricinoleic acid. Therefore, castor oil usually contains a triester of three molecules of ricinoleic acid and one molecule of glycerol, as well as a triester of two molecules of ricinoleic acid and one molecule of castor oil constituent fatty acid other than ricinoleic acid and one molecule of glycerol. Examples of castor oil constituent fatty acids other than ricinoleic acid include palmitic acid, stearic acid, oleic acid, linoleic acid, and linolenic acid. The number of hydroxyl groups in the castor oil-based polyol (B1) can be 2 to 3, and may be 2.2 to 2.8 or 2.5 to 2.9. The flexible polyurethane foam forming composition according to this disclosure can form a flexible polyurethane foam with high heat resistance by containing the castor oil-based polyol (B1). The castor oil-based polyol (B1) may be one type or two or more types.

[0042] The weight-average molecular weight of the castor oil-based polyol (B1), determined by gel filtration chromatography (GPC), may be 500 to 1500, 700 to 1200, or 850 to 1050, from the viewpoint of making it easier to obtain a flexible polyurethane foam with better hardness.

[0043] The content of castor oil-based polyol (B1) in the flexible polyurethane foam forming composition according to this disclosure may be 10 to 50% by mass or 20 to 40% by mass, based on the total mass of the flexible polyurethane foam forming composition.

[0044] The content of castor oil-based polyol (B1) in the flexible polyurethane foam forming composition according to this disclosure may be 20 to 70% by mass, 20 to 65% by mass, or 20 to 60% by mass, based on the total mass of castor oil-based polyol (B1), polyether polyol (B2), and other active hydrogen-containing compounds contained in the flexible polyurethane foam forming composition.

[0045] Polyether polyol (B2) contains polyether polyol (b2) which has 2 hydroxyl groups. ｐｒｉ Examples of polyoxyethylene polyoxypropylene polyols include polyoxypropylene polyols, polyoxypropylene polyols, and polytetramethylene glycol. From the viewpoint of high molding stability of polyurethane foam, polyoxyethylene polyoxypropylene polyol may also be used.

[0046] In this disclosure, the number of functional groups such as the number of hydroxyl groups in a compound means a value determined based on the chemical structural formula of the compound. For example, a polyether polyol (b2) has two hydroxyl groups. ｐｒｉ ) is b2 ｐｒｉ Based on the chemical formula (i.e., the chemical formula of the target product free of impurities), this means that the number of hydroxyl groups is 2. The number of functional groups, such as the number of hydroxyl groups, can be determined, for example, by known methods, for example, １３ This can be determined by identifying the chemical structure of the target compound using methods such as C-NMR, ESI-TOF / MS, and MALDI-TOF / MS. Furthermore, polyether polyols (b2 ｐｒｉ The number of hydroxyl groups in ) is, for example, １３The chemical structure of the initiator can be determined by identifying it using methods such as C-NMR, ESI-TOF / MS, and MALDI-TOF / MS. Furthermore, the number of functional groups, such as the number of hydroxyl groups in a compound, can also be determined by identifying its chemical structure based on the synthesis process of the compound. For example, a polyether polyol produced by repeatedly ring-opening and adding alkylene oxide using an initiator with two active hydrogen groups can be determined to have two hydroxyl groups.

[0047] Furthermore, as mentioned above, polyether polyols (b2) have two hydroxyl groups. ｐｒｉ ) may be the main product (the most abundant product on a molar basis) in the reaction between an initiator having two active hydrogen groups and an alkylene oxide. Examples of initiators having two active hydrogen groups include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 3-methyl-1,5-pentanediol, 3,3-dimethylolheptane, diethylene glycol, dipropylene glycol, neopentyl glycol, cyclohexane-1,4-diol, cyclohexane-1,4-dimethanol, dimer acid diol, bisphenol A, bis(β-hydroxyethyl)benzene, xylylene glycol, etc. Examples of alkylene oxides include ethylene oxide, propylene oxide, butylene oxide, etc.

[0048] In this disclosure, polyether polyol (B2) is defined as polyether polyol (b2) ｐｒｉ ) May contain polyethers with 0 or 1 hydroxyl group, which are impurities or by-products during synthesis. For example, polyether polyol (B2) may contain polyether polyol (b2) with 2 hydroxyl groups. ｐｒｉ ) may consist only of a polyether polyol (b2) having 2 hydroxyl groups. ｐｒｉ ) An impurity during synthesis, a polyether (b2) with a different number of hydroxyl groups than 2. ｂｙ) may also contain. In the latter case, polyether polyol (B2) is a polyether polyol (b2) having 2 hydroxyl groups. ｐｒｉ ) and polyethers with a different number of hydroxyl groups (b2 ｂｙ ) may consist only of a polyether polyol (b2) having 2 hydroxyl groups. ｐｒｉ ), or a mixture of a polyether polyol having 1 hydroxyl group and a polyether having 0 hydroxyl groups.

[0049] Polyether polyol (B2) is, for example, a reaction product of an initiator with two active hydrogen groups and an alkylene oxide. In the reaction of an initiator with two active hydrogen groups and an alkylene oxide, the above polyether polyol with two hydroxyl groups is synthesized, as well as polyether (b2) with a different number of hydroxyl groups. ｂｙIn some cases, a by-product may be generated and remain as an impurity. For example, the above reaction can be carried out in the presence of a basic catalyst, in which case the alkylene oxide is deprotonated and ring-opened in the presence of the basic catalyst to be converted to an alkenyl oxide anion, and the alkylene oxide is repeatedly ring-opened and added using the alkenyl oxide anion as an initiator, thereby generating a polyether monool having one ethylenically unsaturated bond (derived from the above alkenyl oxide anion) as an impurity. For the mechanism of such impurity generation, see, for example, "Susumu Sato, Masahiro Saito, and Kingo Miura. "Excess ratio and unsaturated bond in alkylene oxide addition polymerization." Journal of Industrial Chemistry 69.3 (1966): 501-505.", "Ryozo Motoyama. "Production of polyalkylene oxides and their uses." Journal of Synthetic Organic Chemistry, Japan 23.3 (1965): 267-272." Furthermore, for example, in the reaction of an initiator with two active hydrogen groups with an alkylene oxide in the presence of a basic catalyst, the alkoxide anion obtained by repeated ring-opening addition of the alkylene oxide to the initiator undergoes a chain transfer reaction with the alkylene oxide, converting the terminal alkoxide group of the alkoxide anion to an alkenyl group with the same number of carbon atoms. This can result in the formation of a polyether monool having one ethylenically unsaturated bond (derived from the alkenyl group) and / or a polyether having two ethylenically unsaturated bonds (derived from the alkenyl group) and zero hydroxyl groups as an impurity. For the mechanism of such impurity formation, see, for example, "Ryozo Motoyama. "Production of Polyalkylene Oxides and Their Applications." Journal of Synthetic Organic Chemistry, Japan 23.3 (1965): 267-272." As described above, polyethers with a different number of hydroxyl groups (b2 ｂｙ ) can be a polyether having 0 or 1 hydroxyl group, or a polyether having 1 hydroxyl group. Also, a polyether (b2) with a different number of hydroxyl groups as an impurity. ｂｙ) is likely to be generated when propylene oxide and / or butylene oxide are used as the alkylene oxide, and is particularly likely to be generated when propylene oxide is used as the alkylene oxide. Furthermore, polyether (b2) is produced as a by-product impurity. ｂｙ ) is included in the reaction product of an initiator with two active hydrogen groups and an alkylene oxide.

[0050] Polyether polyol (b2) has 2 hydroxyl groups. ｐｒｉ ) and the polyether polyol (b2 ｐｒｉ ) Polyethers (b2) that have a different number of hydroxyl groups than 2, which are impurities during synthesis. ｂｙ The number-average molecular weight of the mixture may be 500 to 10,000, 1,000 to 8,000, or 2,000 to 6,000, from the viewpoint of making it easier to obtain a flexible polyurethane foam with better hardness. When the number-average molecular weight of the mixture is 500 or more, the flexible polyurethane foam has sufficient flexibility, and when the number-average molecular weight is 10,000 or less, the hardness of the flexible polyurethane foam tends to improve.

[0051] The content of polyether polyol (B2) in the flexible polyurethane foam forming composition according to this disclosure may be 5 to 50% by mass or 20 to 40% by mass, based on the total mass of the flexible polyurethane foam forming composition.

[0052] The content of polyether polyol (B2) in the flexible polyurethane foam forming composition according to this disclosure may be 5 to 60% by mass, 10 to 60% by mass, or 20 to 60% by mass, based on the total mass of castor oil-based polyol (B1), polyether polyol (B2), and other active hydrogen-containing compounds contained in the flexible polyurethane foam forming composition.

[0053] The total content of castor oil-based polyol (B1) and polyether polyol (B2) in the flexible polyurethane foam forming composition according to this disclosure may be 20 to 80% by mass or 30 to 70% by mass, based on the total mass of the flexible polyurethane foam forming composition.

[0054] The total content of castor oil-based polyol (B1) and polyether polyol (B2) in the flexible polyurethane foam forming composition according to this disclosure may be 25 to 95% by mass, 30 to 95% by mass, or 40 to 95% by mass, based on the total mass of castor oil-based polyol (B1), polyether polyol (B2), and other active hydrogen-containing compounds contained in the flexible polyurethane foam forming composition.

[0055] Polyether polyol (B2) has 2 hydroxyl groups, which is polyether polyol (b2) ｐｒｉ ) and the polyether polyol (b2 ｐｒｉ ) Polyethers (b2) that have a different number of hydroxyl groups than 2, which are impurities during synthesis. ｂｙ The average hydroxyl group number FB2 calculated by the following formula (1) may be 1.6 to 1.95, 1.65 to 1.9, 1.7 to 1.85, or 1.75 to 1.8, from the viewpoint of improving the elongation of the flexible polyurethane foam.

[0056] [In the formula, OHV represents the total hydroxyl value (mgKOH / g) of the polyether polyol (B2) calculated according to Method B of JIS K 1557-1:2007, and IHD represents the degree of unsaturation (meq / g) of the polyether polyol (B2) calculated according to JIS K 1557-3:2007.]

[0057] Castor oil-based polyol (B1) and polyether polyol (b2) having 2 hydroxyl groups ｐｒｉ ) can be polyadded with polyisocyanate (A) to form polyurethane.

[0058] The flexible polyurethane foam forming composition according to this disclosure may contain at least one crosslinking agent (B3) selected from the group consisting of glycerin, ethylene glycol, diethanolamine, and triethanolamine. The crosslinking agent can improve the hardness of the flexible polyurethane foam and the curability during molding of the flexible polyurethane foam.

[0059] The content of the crosslinking agent (B3) in the flexible polyurethane foam forming composition according to this disclosure may be 0.1 to 5% by mass or 0.5 to 4% by mass, based on the total mass of the flexible polyurethane foam forming composition.

[0060] The content of the crosslinking agent (B3) in the flexible polyurethane foam forming composition according to this disclosure may be 0.1 to 5% by mass or 0.5 to 4% by mass, based on the total mass of the castor oil-based polyol (B1), polyether polyol (B2), and other active hydrogen-containing compounds in the flexible polyurethane foam forming composition.

[0061] The composition for forming flexible polyurethane foam according to this disclosure may contain a connecting agent (B4) from the viewpoint of improving the air permeability, durability, etc., of the foam. The connecting agent (B4) may contain a polyether polyol having four hydroxyl groups and a polyoxyalkylene chain made of a copolymer of oxyethylene and oxypropylene. The number average molecular weight of the polyether polyol may be 3,000 to 8,000. The weight average molecular weight of the polyether polyol determined by GPC may be 5,000 to 11,000 or 7,000 to 9,000 from the viewpoint of making it easier to obtain a flexible polyurethane foam with better hardness. The oxyethylene units in the polyether polyol may be 60 to 90% by mass or 60 to 80% by mass from the viewpoint of easily improving the durability of the foam. By setting the oxyethylene units in the polyether polyol to 60 to 90% by mass, the durability of the foam can be improved. Furthermore, from the viewpoint of storage stability at low temperatures, the copolymer made of oxyethylene and oxypropylene may be a random copolymer.

[0062] The above-mentioned connecting agent (B4) may be a reaction product of an initiator having 4 active hydrogen groups and an alkylene oxide, and may contain polyethers having a different number of hydroxyl groups, which are impurities during the synthesis of the polyether polyol having 4 hydroxyl groups. In this case, the average number of hydroxyl groups FB4 of the polyether polyol having 4 hydroxyl groups and the polyethers having a different number of hydroxyl groups, calculated by the following formula (2), may be 3.0 to 4.0.

[0063] [In the formula, OHV represents the total hydroxyl value (mgKOH / g) of the connecting agent (B4) calculated according to Method B of JIS K 1557-1:2007, and IHD represents the total degree of unsaturation (meq / g) of the connecting agent (B4) calculated according to JIS K 1557-3:2007.]

[0064] The content of the communicating agent (B4) in the flexible polyurethane foam forming composition according to this disclosure may be 0.1 to 5% by mass or 0.5 to 4% by mass, based on the total mass of the flexible polyurethane foam forming composition.

[0065] The content of the communicating agent (B4) in the flexible polyurethane foam forming composition according to this disclosure may be 0.1 to 10% by mass or 0.5 to 4% by mass, based on the total mass of the castor oil-based polyol (B1), polyether polyol (B2), and other active hydrogen-containing compounds contained in the flexible polyurethane foam forming composition.

[0066] The flexible polyurethane foam forming composition according to this disclosure may contain polyols other than those described above. Examples of such polyols include polyester polyols. Examples of polyester polyols include a polycondensation type polyester polyol consisting of adipic acid and a diol, and a lactone-based polyester polyol such as polycaprolactone polyol.

[0067] The total polyol content in the flexible polyurethane foam forming composition according to this disclosure may be 30 to 80% by mass or 40 to 70% by mass, based on the total mass of the flexible polyurethane foam forming composition.

[0068] Examples of the foaming agent (C) include water and low-boiling point organic compounds such as cyclopentane and isopentane. A combination of water and a low-boiling point organic compound is used, or water alone may be used, as low-boiling point organic compounds lose weight due to volatilization and the amount added is less stable compared to water. Water has two active hydrogen groups that react with isocyanate groups. The reaction between these active hydrogen groups and isocyanate groups forms a high-hardness urea group and generates carbon dioxide, which causes foaming.

[0069] Furthermore, air, nitrogen gas, liquefied carbon dioxide, etc., can be used as the foaming agent (C). In the production of flexible polyurethane foam (i.e., the reaction product of the flexible polyurethane foam forming composition according to this disclosure), air, nitrogen gas, liquefied carbon dioxide, etc., can be mixed and dissolved into the flexible polyurethane foam forming composition using a gas loading device to cause foaming.

[0070] The water content as a foaming agent (C) in the flexible polyurethane foam forming composition according to this disclosure may be 0.1 to 10% by mass, 0.1 to 5% by mass, or 0.5 to 2% by mass, based on the total mass of the flexible polyurethane foam forming composition. By keeping the water content below these upper limits, foaming can be stably produced, resulting in stable performance of the flexible polyurethane foam. By keeping the water content above these lower limits, the density of the foam can be sufficiently increased.

[0071] The composition for forming flexible polyurethane foam according to this disclosure may contain catalyst (D). Known urethane catalysts can be used as catalyst (D), and examples include amine catalysts such as triethylamine, tripropylamine, tributylamine, N-methylmorpholine, N-ethylmorpholine, dimethylbenzylamine, N,N,N',N'-tetramethylhexamethylenediamine, N,N,N',N',N''-pentamethyldiethylenetriamine, bis-(2-dimethylaminoethyl) ether, triethylenediamine, 1,8-diazabicyclo[5.4.0]undecene-7, 1,2-dimethylimidazole, dimethylethanolamine, N,N-dimethyl-N-hexanolamine, N,N-dimethylethanolamine, and N,N-diethylethanolamine; organic salts thereof; organometallic compounds such as stanus octoate and zinc naphthenate. From the viewpoint of minimizing the risk of deterioration over time such as heat resistance and water resistance, it may be an amine catalyst or triethylenediamine. The catalyst (D) may be one type or two or more types.

[0072] The content of catalyst (D) in the flexible polyurethane foam forming composition according to this disclosure may be 0.05 to 3% by mass or 0.1 to 1.5% by mass, based on the total mass of the flexible polyurethane foam forming composition.

[0073] The flexible polyurethane foam forming composition according to this disclosure may contain a foam stabilizer (E). The foam stabilizer (E) may be a known surfactant, and from the viewpoint of having a high effect in making bubbles uniform and stabilizing, it may be a silicone-based surfactant (i.e., a silicone-based foam stabilizer). Examples of silicone-based foam stabilizers include TF1365, SZ-1327, SZ-1325, SZ-1336, SZ-3601 from Dow Toray, Y-10366J, L-5309J from Momentive, and B-8724LF2, B-8715LF2 from Evonik. The foam stabilizer (E) may be one type or two or more types. Silicone-based foam stabilizers usually have polysiloxane chains.

[0074] The content of the foam stabilizer (E) in the flexible polyurethane foam forming composition according to this disclosure may be 0.1 to 3% by mass or 0.3 to 1.5% by mass, based on the total mass of the flexible polyurethane foam forming composition.

[0075] The flexible polyurethane foam forming composition according to this disclosure may further contain, in addition to the components described above, various known additives such as antioxidants, colorants, flame retardants, plasticizers, and antifungal agents, fillers such as calcium carbonate and barium sulfate, and other components such as auxiliary agents. The total content of these other components in the flexible polyurethane foam forming composition according to this disclosure may be 0 to 30% by mass, 0 to 10% by mass, or 0 to 5% by mass, based on the total mass of the flexible polyurethane foam forming composition according to this disclosure.

[0076] Examples of antioxidants include hindered phenol antioxidants, hindered amine antioxidants, thioether antioxidants, and phosphite antioxidants. From the viewpoint of providing long-term stability to the flexible polyurethane foam in high-temperature environments, a hindered phenol antioxidant may also be used. There may be one antioxidant or two or more antioxidants.

[0077] As a hindered phenol antioxidant, from the viewpoint of being liquid at room temperature and having good miscibility with other components, esters of 3,5-bis(1,1-dimethylethyl)-4-hydroxybenzenepropionic acid with an alkyl alcohol having 7 to 9 carbon atoms and a branched structure (Irganox 1135 from BASF Japan), esters of 3,5-bis(1,1-dimethylethyl)-4-hydroxybenzenepropionic acid with an alkyl alcohol having 18 carbon atoms (Irganox 1076 from BASF Japan), etc. may be used.

[0078] The content of the antioxidant in the flexible polyurethane foam forming composition according to this disclosure may be 0.01 to 5% by mass or 0.1 to 1% by mass, based on the total mass of the flexible polyurethane foam forming composition. The content of the hindered phenol antioxidant in the flexible polyurethane foam forming composition according to this disclosure may be 0.01 to 5% by mass or 0.1 to 1% by mass, based on the total mass of the flexible polyurethane foam forming composition.

[0079] Examples of colorants include inorganic pigments such as carbon black, graphite, manganese black, and cobalt black. The colorants may be one type or two or more types.

[0080] The colorant content in the flexible polyurethane foam forming composition according to this disclosure may be 0.1 to 10% by mass or 0.1 to 5% by mass, based on the total mass of the flexible polyurethane foam forming composition. The carbon black content in the flexible polyurethane foam forming composition may be 0.1 to 10% by mass or 0.1 to 2.5% by mass, based on the total mass of the flexible polyurethane foam forming composition.

[0081] The flexible polyurethane foam forming composition according to this disclosure may be a two-component composition in which the active hydrogen-containing compound is separated from the polyisocyanate (A). For example, the active hydrogen-containing compound and the polyisocyanate (A) may be contained in separate containers.

[0082] The flexible polyurethane foam according to this disclosure can be manufactured, for example, by thoroughly mixing a polyisocyanate (A), a castor oil-based polyol (B1), a polyether polyol (B2) containing a polyether polyol with two hydroxyl groups, and a blowing agent (C), and then reacting and foaming them.

[0083] Specifically, methods such as injecting a mixture of polyisocyanate (A), castor oil-based polyol (B1), polyether polyol containing a polyether polyol with two hydroxyl groups (B2), and a foaming agent (C) (hereinafter also referred to as "foaming stock") into a mold and then foaming and curing it to produce flexible polyurethane mold foam (hereinafter sometimes referred to as "flexible mold foam"), or supplying the foaming stock into a foaming container or continuously onto a belt conveyor and foaming it to produce flexible polyurethane slab foam (hereinafter sometimes referred to as "flexible slab foam") can be employed.

[0084] Polyisocyanate (A), castor oil-based polyol (B1), polyether polyol (B2) containing a polyether polyol with 2 hydroxyl groups, and blowing agent (C) may be mixed so as to have an isocyanate index of 70 to 140, or from the viewpoint of improving the molding cycle, they may be mixed so as to have an isocyanate index of 70 to 120. The isocyanate index is the percentage of the total number of isocyanate groups of polyisocyanate (A) to the total number of active hydrogen groups of the active hydrogen-containing compounds (total number of isocyanate groups / total number of active hydrogen groups × 100).

[0085] In the manufacture of flexible mold foam, the mold temperature when injecting the foaming liquid into the mold may be 30 to 80°C or 45 to 70°C. A mold temperature of 30°C or higher improves the reaction rate and production cycle, while a mold temperature of 80°C or lower prevents excessive acceleration of the reaction between water and isocyanate compared to the reaction between polyol and isocyanate, thereby suppressing foam collapse during the foaming process.

[0086] The curing time when foaming and hardening the foam concentrate can be 10 minutes or less, or even 7 minutes or less, considering the production cycle of a typical flexible mold foam.

[0087] When manufacturing flexible molded foam, the above components can be mixed using a high-pressure foaming machine, a low-pressure foaming machine, etc., as with ordinary flexible molded foam.

[0088] The polyisocyanate (A), castor oil-based polyol (B1), polyether polyol (B2) containing a polyether polyol with two hydroxyl groups, and the foaming agent (C) may be mixed immediately before foaming, as this allows for adjustment of the mixing ratio each time. The mixture (foaming concentrate) may be used immediately after mixing, or it may be stored and used as needed.

[0089] Furthermore, the mixing method may be dynamic mixing, which is performed in the mixing chamber of the foaming machine's machine head, or static mixing, which is performed in the liquid delivery piping, or both may be used in combination. Static mixing is often used for mixing gaseous components such as physical foaming agents with liquid components, while dynamic mixing is often used for mixing components that can be stably stored as liquids. The foaming device may be a high-pressure foaming device that does not require solvent cleaning of the mixing section.

[0090] The mixture obtained by this mixing process is injected into a mold, allowed to foam and harden, and then demolded. The mold used in the manufacture of flexible polyurethane foam should have voids to contain the above-mentioned mixture and be made of a material that can withstand the pressure and heat generated by the reaction. The mold may also be temperature-controlled and may be capable of proceeding with the reaction by heating it while containing the above-mentioned mixture.

[0091] The shape and thickness of the flexible polyurethane foam produced are determined according to the internal shape (shape of the voids) of the mold. Therefore, for example, the internal shape of the mold may be designed so that flexible polyurethane foam of the desired shape is formed.

[0092] If the mold consists of a pair of molds, a release agent or in-mold coating paint may be applied to the inner surface of at least one of the molds beforehand, or a film may be placed in a shape that conforms to the inner surface shape before the mixture is poured into the mold, and the mold may be demolded after foaming and curing. If a film is placed, the film will be peeled off from the flexible polyurethane foam after demolding.

[0093] As release agents, linear hydrocarbon release agents (linear wax-based release agents) and branched hydrocarbon release agents (branched wax-based release agents) can be used. Examples of linear hydrocarbon release agents include paraffin wax, Fischer-Tropsch wax, and sazole wax. Examples of branched hydrocarbon release agents include microcrystalline wax and modified polyethylene wax. One type of release agent may be used, or two or more types may be used in combination. If the release agent contains volatile components such as organic solvents or water in addition to the release component (wax component), these components may be evaporated before introducing the mixture into the mold.

[0094] As a release agent, a release agent having a melting peak temperature of 80°C to 130°C (hereinafter also referred to as "release agent (I)") may be used. By pre-applying release agent (I) to the inner surface of the mold, a flexible polyurethane foam tends to be obtained in which the surface porosity of the surface that was in contact with the mold to which release agent (I) was applied during molding is 20 to 60%.

[0095] The release agent (I) may have two or more melting peak temperatures. If the release agent (I) has two or more melting peak temperatures, it is determined whether the first melting peak temperature (the lowest melting peak temperature) is between 80°C and 130°C.

[0096] The melting peak temperature of the release agent refers to the melting peak temperature in accordance with JIS K 7121:1987. That is, the differential scanning calorimetry (DSC) curve is measured, and the temperature at the peak of the melting peak is defined as the melting peak temperature (Tpm). The DSC curve can be measured after conditioning as described in the above JIS. Specifically, the test specimen is placed in the container of the DSC apparatus, heated and melted to a temperature approximately 30°C higher than the end of the melting peak, maintained at that temperature for 10 minutes, and then cooled at a cooling rate of 5°C / min or 10°C / min to a temperature at least approximately 50°C lower than the resulting transition peak, thereby conditioning the specimen. Immediately after conditioning, the apparatus is stabilized and heated at a heating rate of 10°C / min to a temperature approximately 30°C higher than the end of the melting peak, and a DSC curve is generated. From this DSC curve, the temperature at the peak of the melting peak is identified as the melting peak temperature. If multiple peaks are observed, it is assumed that there are multiple melting peak temperatures. When there are multiple melting peak temperatures, they are referred to in order from the lowest temperature, such as the first melting peak temperature, the second melting peak temperature, and so on.

[0097] As a release agent, a release agent having a melting peak temperature of 40°C or higher and less than 70°C (hereinafter also referred to as "release agent (II)") may be used. By pre-applying release agent (II) to the inner surface of the mold, a flexible polyurethane foam tends to be obtained in which the surface that was in contact with the mold to which release agent (II) was applied during molding has a surface porosity of 0 to 1.0%.

[0098] The release agent (II) may have two or more melting peak temperatures. If the release agent (II) has two or more melting peak temperatures, it is determined whether the first melting peak temperature is 40°C or higher and less than 70°C.

[0099] The in-mold coating paint may be water-based or solvent-based, and may be a one-component or two-component curing type. From the viewpoint of the working environment, the in-mold coating paint may be a water-based one-component curing type. Examples of resins for the in-mold coating paint include known paints such as polyurethane resin, acrylic resin, and polyester resin. By pre-applying the in-mold coating paint to the inner surface of the mold, a flexible polyurethane foam tends to be obtained in which the surface porosity of the surface that was in contact with the mold to which the in-mold coating paint was applied during molding is 0 to 1.0%.

[0100] The film can be an opaque resin film. Examples of resins include polyurethane resin, acrylic resin, polyethylene resin, polypropylene resin, vinyl chloride resin, EVA resin, PBT resin, silicone rubber, and polyamide resins such as 6-nylon, 6,6-nylon, 11-nylon, and 12-nylon. By pre-placing the film on the inner surface of the mold, a flexible polyurethane foam tends to be obtained in which the surface porosity of the film that was in contact with the mold during molding is 0 to 1.0%.

[0101] The demolded flexible polyurethane foam can be used as is, but the cell membrane of the foam may be broken under compression or reduced pressure by known methods to stabilize the appearance and dimensions of the product thereafter. In addition, the main surface of the demolded flexible polyurethane foam may be subjected to perforation treatments such as needle punching, hot needle processing, or laser irradiation, to the extent that it does not impair the sound absorption and insulation performance.

[0102] The flexible polyurethane foam according to this disclosure can be used as a foam member comprising the flexible polyurethane foam. The foam member can be used to cover at least a part of an object that emits vibration or sound (sound-producing object). The foam member may consist only of the flexible polyurethane foam according to this disclosure, or it may have laminates such as films, components, etc. on all or part of the surface of the flexible polyurethane foam according to this disclosure. The foam member can be arranged so that the first surface of the flexible polyurethane foam according to this disclosure faces the object. Since the flexible polyurethane foam according to this disclosure has sound absorption and sound insulation properties, the foam member can also be called a soundproofing member.

[0103] The foam member may be positioned so as to be in contact with part or all of the object, or it may be positioned at a predetermined distance from the object. In the latter case, other members may be inserted between the object and the foam member. When the foam member is in contact with the object, the foam member may be in direct contact with the object (in particular, the soft polyurethane foam provided by the foam member may be in direct contact with the object), or the foam member may be bonded to the object via other members such as adhesives. In any of the above cases, a fixing device may be used to position the foam member so as to be in contact with part or all of the object.

[0104] The shape of the foam member and the flexible polyurethane foam contained within it are arbitrary, and may be a shape that fits the shape of the entire object or a part thereof. The foam member can be pre-molded to conform to the outer surface (outer wall) of the object, and the molded foam member can be fitted onto the object to cover at least a part of the outer surface. Alternatively, the foam member can be molded into a plate shape (including a film shape), and the molded foam member can be wrapped around the object to cover at least a part of the object. The thickness of the foam member or the flexible polyurethane foam contained within it can be any value depending on the level of sound emitted by the object or the sound absorption and insulation performance required of the foam member. For example, the thickness of the foam member or the flexible polyurethane foam contained within it can be 5.0 to 50 mm, 10 to 40 mm, or 10 to 30 mm.

[0105] Because the flexible polyurethane foam relating to this disclosure has the excellent performance described above, it can be used in components that require sound absorption and insulation properties, such as dash insulators.

[0106] The present disclosure will be described in more detail below with reference to examples.

[0107] [Formation of Flexible Polyurethane Foam] [Raw Materials, etc.] In the formation of flexible polyurethane foam, the raw materials, etc. described below were used. Polyisocyanate 1: A polyisocyanate (manufactured by Tosoh Corporation, "CEF-538") containing 70% by mass of diphenylmethane diisocyanate (MDI) and 24% by mass of polymethylene polyphenylene polyisocyanate (polymeric MDI, P-MDI). The total content of 2,4'-MDI and 2,2'-MDI (isomer content) is 17.7% by mass based on the total amount of MDI. The content of MDI relative to the total amount of MDI and P-MDI is approximately 74% by mass. The isocyanate group content is 28.8% by mass. Castor oil-based polyol 1: A castor oil-based polyol (manufactured by Giant Agro, "H-300") made from refined castor oil with an average number of hydroxyl groups of 2.7, a hydroxyl value of 160 (mg KOH / g), and a weight-average molecular weight of 945 determined by GPC. Polyether polyol 1: A polyoxyethylene polyoxypropylene polyol (manufactured by Kagaku Chemical Co., Ltd., "Puranol D-4021") with a nominal number of hydroxyl groups of 2. The hydroxyl value of polyether polyol 1 as a whole (including polyether, which is an impurity during the synthesis of polyoxyethylene polyoxypropylene polyol. The number of hydroxyl groups determined based on the chemical structural formula of the polyoxyethylene polyoxypropylene polyol is 2) is 28 (mg KOH / g), and the number-average molecular weight is 4000. Polyether polyol 2: A polyoxyethylene polyoxypropylene polyol (manufactured by Tosoh Corporation, "NEF-024") with a nominal number of hydroxyl groups = 4 and oxyethylene units = 80% by mass. The hydroxyl value of polyether polyol 2 as a whole (including polyether, which is an impurity during the synthesis of polyoxyethylene polyoxypropylene polyol; the number of hydroxyl groups determined based on the chemical structural formula of the polyoxyethylene polyoxypropylene polyol is 4) is 28 (mgKOH / g), and the weight-average molecular weight determined by GPC is 8000.Glycerin 1: Manufactured by NOF Corporation, Glycerin DG Diethanolamine 1: Manufactured by Nippon Shokubai Co., Ltd., Diethanolamine Amine Catalyst 1: Amine catalyst (manufactured by Tosoh Corporation, "TEDA-L33") Amine Catalyst 2: Amine catalyst (manufactured by Tosoh Corporation, "TOYOCAT-ET") Silicone-based foam stabilizer 1: Silicone-based foam stabilizer (manufactured by Dow Toray, "TF1365") Antioxidant: Hindered phenol-based antioxidant (manufactured by BASF Japan, "Irganox 1135") Coloring agent: Carbon black (manufactured by Kagaku Chemical Co., Ltd., "3U53D") Release agent 1: Linear wax-based release agent with first melting peak temperature = 87.8°C and second melting peak temperature = 99.5°C (manufactured by Chukyo Oil & Fat Co., Ltd., "T-626") (corresponding to release agent (I) in the above embodiment) Release agent 2: Branched chain wax-based release agent with a first melting peak temperature of 50.4°C and a second melting peak temperature of 91.4°C (manufactured by Chukyo Oil & Fat Co., Ltd., "M-975") (corresponding to release agent (II) in the above embodiment) Paint 1: Water-based one-component curing paint (manufactured by Fujikura Chemical Co., Ltd., "458W") Paint 2: Water-based one-component curing paint (manufactured by Everlight Co., Ltd., "PUD-7831") Film 1: Low-density polyethylene film (manufactured by Tosoh Corporation, "Petrocene 250R").

[0108] Table 1 shows the results of determining the degree of unsaturation (meq / g) of polyether polyols 1 and 2 in accordance with JIS K 1557-3:2007. As shown in Table 1, since neither polyether polyol 1 nor 2 had a degree of unsaturation of 0, it was indicated that polyether polyols 1 and 2 contain polyether, which is an impurity from the synthesis of polyether polyols.

[0109] As described above, the number of hydroxyl groups in polyether polyols 1 and 2 is 2 and 4, respectively. Also, as described above, the hydroxyl value of polyether polyols 1 and 2 is 28 (mg KOH / g). Based on this, the hydroxyl value and the degree of unsaturation, the average number of hydroxyl groups of the polyether polyols and the polyether impurities calculated by formula (1) is shown in Table 1 below.

[0110]

[0111] [Preparation of Composition Containing Active Hydrogen Compounds] Each component listed in "Composition Containing Active Hydrogen Compounds" in Table 2 below was weighed into a polypropylene cup (1 L) in the amounts (unit: parts by mass) listed in Table 2. The mixture was then mixed using a small high-speed stirrer (PRIMIX, Inc., "PRIMIX") at 1400 revolutions per minute for 20 minutes at room temperature of 25°C to obtain composition P-1 containing active hydrogen compounds.

[0112] [Formation of Flexible Polyurethane Foam] Composition P-1 containing an active hydrogen-containing compound was mixed with polyisocyanate 1 as shown in Table 2 in the amount shown in Table 2, and mixed for 7 seconds at 7000 revolutions per minute using a small high-speed stirrer (PRIMIX, Inc.) to prepare the foaming stock solutions for Examples 1-4 and Comparative Examples 1-4. Immediately after preparing the foaming stock solutions, they were injected into a mold to foam the flexible polyurethane foam. The foaming was carried out under the following conditions. In the Examples and Comparative Examples, the release agent and in-mold coating paint shown with a "○" in Table 2 were applied to the upper and lower sides of the mold beforehand, and a film was placed (areas without a "○" in the release agent, in-mold coating paint, and film indicate that they were not used). After that, the flexible polyurethane foam molded body was removed from the mold. <Foaming Conditions> Mold temperature: 55-65°C Mold shape: 300 mm x 300 mm x 10 mm Mold material: Aluminum Cure time: 6 minutes

[0113] In Table 2, the "Isocyanate Index" refers to the percentage of the total number of isocyanate groups of polyisocyanate (A) relative to the total number of active hydrogen groups of castor oil-based polyol 1, polyether polyols 1-2, glycerin 1, diethanolamine 1, and water in the above-mentioned foaming stock solution (total number of isocyanate groups / total number of active hydrogen groups × 100). The number of active hydrogen groups of polyether polyols 1-2 is based on the "average number of hydroxyl groups of polyether polyols and impurity polyethers" described in Table 1 above.

[0114] [Evaluation of Flexible Polyurethane Foam] The flexible polyurethane foam molded articles formed in Examples 1 to 4 and Comparative Examples 1 to 4 were evaluated based on the following evaluation methods, and the results are shown in Table 2. For the molded article of Example 4, the evaluation was performed after the film was peeled off following demolding. For the molded article of Comparative Example 3, after demolding, the surface that was in contact with the mold on the lower side during molding (hereinafter also referred to as the "lower molded surface") was subjected to a hole-punching treatment by hot needle processing (needle perforation treatment) before evaluation. For the molded article of Comparative Example 4, after demolding, the surface that was in contact with the mold on the upper side during molding (hereinafter also referred to as the "upper molded surface") was subjected to a needle perforation treatment before evaluation.

[0115] [Bulk Density] The apparent density of the entire flexible polyurethane foam molded body in accordance with JIS K 6400-1:2004 (unit: kg / m³) ３ The bulk density was determined by measuring the volume (W). Specifically, a rectangular sample (200 mm long x 200 mm wide x 10 mm thick) was cut from a molded flexible polyurethane foam, and its weight (W) was measured. Next, the volume (V) was determined from the length, width, and thickness of the rectangular sample, and the density (ρ) was calculated by dividing the weight (W) by the volume (V).

[0116] [F Hardness] The F hardness was measured for the upper molded surface of each soft polyurethane foam molded body using a rubber hardness tester (Asker F type).

[0117] [Average Bubble Diameter] The average bubble diameter of each soft polyurethane foam molded body was evaluated. Specifically, first, a 10 mm thick molded body was cut into a disc shape with a diameter of 28.8 mm, and an image with a field of view of 5.4 mm vertically and 7.2 mm horizontally was taken using a microscope equipped with a Moritex MML08-HR110 lens on the side of the foam. Next, four line segments were drawn in the vertical and horizontal directions on the image, and the number of cells located on each line segment was measured and the arithmetic mean was calculated to obtain the average number of cells. Subsequently, the average cell diameter was obtained by dividing the actual distance of each line (vertical: 5.4 mm, horizontal: 7.2 mm) by the average number of cells. Finally, the average bubble diameter was obtained by dividing the average cell diameter by 0.785.

[0118] [Surface Porroid Ratio] The surface porosity of each flexible polyurethane foam molded body was calculated by cutting a circular section of the 10 mm thick molded body to a diameter of 28.8 mm, and taking images of the upper and lower molded surfaces using a microscope equipped with a Moritex MM014-HR110-5M telecentric lens. The images were then binarized using the "ImageJ" software to separate the porosity from the rest of the surface, and the total area of ​​the porosity was calculated. The surface porosity was then calculated based on the following formula: Surface Porrosion Ratio = (Total Area of ​​Porosity / Sample Area) × 100

[0119] [Air permeability] Air permeability of flexible polyurethane foam in accordance with JIS K 6400-7:2012 (unit: cm) ３ / cm ２ The / sec) value was measured.

[0120] [Sound Absorption Coefficient] Based on the method described in JIS A 1405-2:2007, the normal incidence sound absorption coefficient was measured at 500 to 6300 Hz using a Bruel Kjær Japan Type 4206 acoustic tube. The sound absorption coefficient was measured by placing a flexible polyurethane foam molded body with a diameter of 28.8 mm and a thickness of 10 mm with the upper molded surface facing the sound source, and without providing an air layer behind the flexible polyurethane foam molded body. The average sound absorption coefficient at 1000 to 6300 Hz was calculated as the simple average of the normal incidence sound absorption coefficients at 1000 Hz, 1250 Hz, 1600 Hz, 2000 Hz, 2500 Hz, 3150 Hz, 4000 Hz, 5000 Hz, and 6300 Hz.

[0121] [Transmission Loss] The normal incidence transmission loss from 12.5 to 1600 Hz was measured using a Bruel Kjær Japan Model 4206 acoustic tube, based on the method described in ASTM E2611. The transmission loss was measured using a flexible polyurethane foam molded body with a diameter of 100 mm and a thickness of 10 mm, with the upper molded surface facing the sound source, and no air layer was provided behind the flexible polyurethane foam molded body. The average transmission loss (in dB) from 630 to 1600 Hz was calculated as the simple average of the normal incidence transmission losses at 630 Hz, 800 Hz, 1000 Hz, 1250 Hz, and 1600 Hz.

[0122] [Moldability] The moldability of the flexible polyurethane foam was evaluated. Specifically, a "○" was given if the flexible polyurethane foam could be molded without phenomena such as collapse (where the flexible polyurethane foam sinks significantly after reaching its maximum height) or shrinkage of the generated flexible polyurethane foam immediately after foaming or after curing.

[0123]

Claims

1. A flexible polyurethane foam having a first surface with a surface porosity of 20-60% and a second surface with a surface porosity of 0-1.0%.

2. Bulk density of 80-140 kg / m³ ３ The flexible polyurethane foam according to claim 1.

3. The flexible polyurethane foam according to claim 1 or 2, wherein the average cell diameter is 0.3 to 0.8 mm.

4. The flexible polyurethane foam according to claim 1 or 2, wherein the F hardness is 25 to 95.

5. The air permeability measured in accordance with JIS K 6400-7:2012 is 0 to 1.0 cm. ３ / cm ２ A flexible polyurethane foam according to claim 1 or 2, wherein the temperature is / sec.

6. The flexible polyurethane foam according to claim 1 or 2, wherein the thickness of the thinnest part is 5.0 to 50 mm.

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